Turkish President Recep Tayyip Erdogan said on Monday that Saudi Arabian authorities have to prove that missing Saudi journalist Jamal Khashoggi had left the Istanbul consulate, reported state-run Anadolu Agency.

"We have to get an outcome from this investigation as soon as possible. The consulate officials cannot get away by simply saying 'he has left' and relevant authorities are obligated to provide proof of this claim," Erdogan told a news conference in Budapest, Hungary, where he is on an official visit.

"It is our humanitarian and political duty to closely follow the issue," said the Turkish leader.

Several unconfirmed reports said that the prominent journalist could have been killed inside the Saudi compound.